The present invention relates to methods and equipment for automated handling of small parts such as electrical and mechanical components, and more particularly, to a feeder designed to separate parts molded to a continuous carrier tape unwound from a supply reel.
Tape and reel supply of small discrete parts such as electrical and mechanical components for automatic pick and place on into a printed circuit board (PCB) or other substrate is widely used in the electronics industry. Examples of pick and place machines are those commercially available from Universal, Panasonic, Fuji and others. Typically the pick and place machines have multiple removable parallel feeders which each support a tape reel carrying a different component. An example of such a feeder is the MPF856 commercially available from Hover-Davis, Inc. In one carrier tape system commercialized by Advantek and 3M a plastic carrier tape with sprocket holes along one or both side edges is embossed to form a series of pockets which each carry a separate component covered by a continuous strip. The carrier tape is unreeled, its cover strip is peeled back, and a pick and place head removes a component adapted for surface mount or through hole from each pocket. The component is placed under precise computer control onto a given location on a PCB. The PCB usually has solder paste applied at precise locations which temporarily holds the component in place until solder reflow.
The aforementioned technique for tape and reel supply of small discrete parts has proven to be widely successful. However, it is costly, inconvenient, and does not provide accurate part location. The U.S. patent of Giuseppe Bianca et al. identified above describes a continuous carrier tape product preferably formed by overmolding one or both sides of a series of longitudinally spaced discrete small parts to one or a spaced pair of continuous flexible film strips. The film strip or strips may be provided with sprocket holes and wound on reels for use with a feeder and a pick and place machine. The parts are individually separated before placement onto a PCB. No embossing step of a plastic carrier is required, no assembly of parts into respective pockets is needed and no cover strip is needed to keep the parts from falling out of their respective pockets More parts can be carried per linear loot of tape. The result is that the cost of the tape and supply reel to the PCB assembler is reduced. In addition, the parts can be removed by either the suction head of a pneumatic pick and place machine or a gripper of a mechanical pick and place machine. The film strips are preferably made of a material capable of withstanding the elevated temperatures required to overmold the plastic parts. Preferably the molding overlap is selected to require the finished tape to be pulled with about three to five pounds of force to separate the part therefrom.
In order to advantageously utilize the new overmolded tape and reel product described in the aforementioned U.S. patent of Giuseppe Bianca et al., it would be desirable to provide a novel feeder capable of utilizing the product with conventional pick and place machines. Such a feeder would have to rapidly and reliably separate an individual part from the carrier tape without damaging the part and without displacing the part such that the head of the pick and place machine would be unable to pick up the same.